The present invention relates to a blow-by gas separator for separating and removing oil contained in the blow-by gas of an engine.
There has heretofore been known a PCV (positive crankcase ventilation) arrangement for returning blow-by gas, that has leaked into the crank case from a combustion chamber of an engine through a gap between a piston and a cylinder wall, back to the combustion chamber to burn it. The blow-by gas contains unburned gases as well as a lubricating oil which is in an atomized form, and it is necessary to separate and remove the oil. For the purpose of separating and removing the oil, the PCV apparatus is provided with a separator which is usually arranged inside a cylinder head cover. In the PCV apparatus in which the separator is arranged inside the cylinder head cover, the blow-by gas that has leaked into the crank case is guided into the separator through an oil chute passage that is formed in the side portion of the engine body and is opened in the upper surface of the cylinder head. While the blow-by gas thus guided into the separator passes through the separator, the oil is separated and removed therefrom and is recirculated into the intake system through the PCV hose. In the case of a V-type engine, however, separators are each provided in both cylinder head covers on the right and left banks and hence, the PCV hoses must be connected to the two separators and must be put together, resulting in an increase in the number of parts and causing the device to become complex. In order to solve this problem, there has been proposed a PCV apparatus having a separator which is provided in a chain case that covers a timing chain provided at a front end of the engine, as disclosed in Japanese Laid-open Patent Publications (Kokai) Nos. 98924/1993 (JP-A 5-98924) and 47157/1998 (JP-A 10-47157). With the separator being provided in the chain case at the front end of the engine, the blow-by gas that is introduced from the crank case into the separator to separate and remove the oil can be returned back to the intake system through a single PCV hose, solving the above-mentioned problem peculiar to the V-type engines. However, there exist actually a chain, a sprocket, a tensioner and the like in the chain case, and with relation with this fact, limitation is put on a space where the separator is arranged. That is, there exists a problem in that it is not possible to secure space enough for separating and removing the oil. Further, in the chain case, the oil circulates to lubricate the chain. When the blow-by gas flows through the chain case, therefore, the oil in the chain case intermingles with the blow-by gas. Consequently, a problem arises that the oil can be hardly separated and removed from the blow-by gas to a sufficient degree, and so flows into the intake system.
It is an object of the present invention to provide a blow-by gas separator that can secure space enough for arranging the separator, can reliably separate and remove the oil from the blow-by gas and can prevent the oil from flowing into the intake system.
In order to accomplish the above-mentioned object according to the present invention, there is provided a blow-by gas separator comprising:
a separator unit mounted on a front end surface of a cylinder block and having accommodation space for accommodating a drive mechanism that transmits driving force of the crank shaft of the engine to a driven shaft; wherein
the separator unit is provided with a blow-by gas passage chamber formed along the outer peripheral edge of an upper part of the accommodation space, and has formed therein a blow-by gas flow-in port and a blow-by gas flowout port which are opened in the blow-by gas passage chamber.
The separator unit is constituted by a frame member with the accommodation space and a recessed portion, as well as a cover member mounted on the recessed portion of the frame member and having a cover member recessed portion to form the blow-by gas passage chamber in cooperation with the recessed portion of the frame member.
Further, a partitioning plate for partitioning the blow-by gas passage chamber into a blow-by gas flow-in chamber and a blow-by gas flow-out chamber is disposed between the frame member and the cover member. The partitioning plate has a passage port for communicating the blow-by gas flow-in chamber with the blow-by gas flow-out chamber, and a blow-by gas flow-in port is opened in the blow-by gas flow-in chamber and a blow-by gas flow-out port is opened in the blow-by gas flow-out chamber.
It is desired that the blow-by gas flow-in port be formed at an higher location than the passage port of the partitioning plate and that the blow-by gas flow-in chamber be provided with a narrowed portion with a reduced cross section between the blow-by gas flow-in port and the passage port.
Further, the lower part of the blow-by gas flow-out chamber is communicated through an oil drain passage with the accommodation space for accommodating the drive mechanism.
It is further desired that the partitioning plate be made of a metallic gasket material.
Further, the cylinder block has a pair of right and left banks which have offset relation to each other along the direction of the crank shaft, and the cover member is arranged in space produced by the offset of the right and left banks.